UNITED NATIONS (AP) — The U.N. envoy to Yemen warned Tuesday that “the streets are heating up” in the country’s restive south and pent-up resentment over more than two decades of unaddressed grievances is reaching “a tipping point.”

Calls for an autonomous state in the south — which was once a separate country — have compounded Yemen’s many problems as the impoverished nation struggles with a resurgent al-Qaida and a deep political crisis.

U.N. special representative Jamal Benomar told the Security Council on Tuesday that a “national dialogue” aimed at mapping out the country’s future must settle the status of the south in order to develop the foundations of a new constitution. He urged southern leaders who are not participating to join the talks.

Since February, he said, there has been a significant increase in the frequency and number of demonstrators flooding the streets.

Yemen has been struggling with a transition to democracy since Arab Spring protests in 2011 forced longtime ruler Ali Abdullah Saleh to step down after 33 years as president. A transitional government led by President Abed Rabbu Mansour Hadi is trying to promote national reconciliation, draft a new constitution and hold elections.

Southerners joined a unified Yemen in 1990, but many protesters are again demanding independence. A 1994 attempt by the south to regain independence was crushed in a three-month civil war.

Benomar said the government’s establishment of two commissions to address the unlawful or illegitimate seizure of property in the south and unjust dismissals of southerners from military or civil service was “an important first step in addressing main grievances.”

But he said the commissions need much greater resources and without further confidence-building measures by the government or tangible improvements in people’s daily lives “the voices of discontent will amplify, narrowing the space for dialogue.”

Benomar warned that the security situation remains fragile in many parts of the country and al-Qaida remains “a lethal threat.”

Most recently, he said, al-Qaida has been trying to establish a foothold in the province of Hadramawt and control territory again, as it did during political turmoil in 2011 that led to Saleh’s resignation.

Benomar also cited an increase in the number of assassinations of mid- and high-level security officials, continued arms smuggling and the amassing of more weapons by key political factions, “creating the conditions for further violence and instability.”

While all these issues remain major concerns, Benomar called the national dialogue, which includes delegates from all major political groups as well as women and youth, “a major achievement” that shows the Yemeni people’s commitment “to choose dialogue over violence and consensus over division.”